*service-name*

The value of this variable is the default value of the
name argument to open-server, which determines the
service name that DDE clients must specify to connect with the Lisp
DDE server opened by open-server. The initial value is
:allegro, meaning that the client should specify
the service name as the string "allegro".

Compatibility note: Starting with release 6.2, this variable is no
longer automatically modified to match the service name that was most
recently passed to open-server. You may still modify the value of
this variable to change the global default for a service name, but to
retrieve the service name that is actually being used by a particular
Lisp process, you must call the function service-name instead.